However, he added: "As a former war crimes prosecutor I have seen many cases involving brutal, inhumane violence and I am very sorry that I have had to deal with such a case in an English town."

Courage of surviving friend

He said the testimony given by the victim who survived the attack that killed Mary-Ann was crucial in securing justice for both of them.

"To relive such a traumatic ordeal while facing the perpetrators took tremendous courage," he said.

"She turned the tables in court. Suddenly the victim was strong and the attackers were vulnerable.

"She has proved that violence and intimidation does not prevent victims finding justice within the courts system.

"I hope these convictions are a source of comfort for the Leneghan family and my thoughts are with them as they come to terms with all that has happened."

In a short statement Mary-Ann's family spoke of their pain.

The statement said: "Mary-Ann was a wonderful girl who was greatly loved by her friends and family, she will be sorely missed. The verdicts today have come nearly a year after she was taken from us. We are now left with the task of trying to piece our lives back together."

After issuing a plea to be left to grieve in peace the family also paid tribute to the people of Reading for their "kindness and compassion" during the past 10 months.

The statement added: "Even people who did not know Mary-Ann were so upset they came together to show support for us."

Detective Superintendent Mark Warwick paid tribute to Mary-Ann's friend who gave evidence against the six killers.

He said: "I would like to pay tribute to the surviving victim, a key witness in this case, who has shown real strength of character throughout this entire process which has been long, arduous and stressful for her."

He added: "There is no doubt in my mind that without the first rate information provided by the witness we would not be where we are today."

Mr Warwick said the murder of Mary-Ann was one of the worst crimes he had encountered in his career.

He said: "I think it is one of the worst, the fact is the duration of the torture, the humiliation, the fear and the ultimate death in the park is horrendous."